Efficient swept sine chirp excitation in the non-linear vibro-acoustic wave modulation technique used for damage detection

In this article, the non-linear vibro-acoustic modulation technique is used for structural damage detection. A new experimental configuration and data processing strategy are proposed to improve the damage detection capability of the technique. The swept sine chirp excitation is used for both low-frequency vibration/modal and high-frequency ultrasonic excitations. The adaptive resampling procedure is then applied to extract information about modulation intensity that relates to damage. The proposed method is illustrated using numerical simulations and experimental tests. The latter involves crack detection in an aluminium beam. The results of the proposed method are compared with the classical approach based on single harmonic excitation, demonstrating that similar damage detection information can be extracted. However, the major advantage of the proposed method is simplicity and robustness since no a priori selection of excitation frequencies is needed. As a result, crack detection is more reliable and unambiguous.